netdev - [PATCH] e1000e: apply burst mode settings only on default

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Message-Id: <20170825150626.2843-1-willemdebruijn.kernel@gmail.com>
Date:   Fri, 25 Aug 2017 11:06:26 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     jeffrey.t.kirsher@...el.com
Cc:     intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        jesse.brandeburg@...el.com, Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH] e1000e: apply burst mode settings only on default

From: Willem de Bruijn <willemb@...gle.com>

Devices that support FLAG2_DMA_BURST have different default values
for RDTR and RADV. Apply burst mode default settings only when no
explicit value was passed at module load.

The RDTR default is zero. If the module is loaded for low latency
operation with RxIntDelay=0, do not override this value with a burst
default of 32.

Move the decision to apply burst values earlier, where explicitly
initialized module variables can be distinguished from defaults.

Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 drivers/net/ethernet/intel/e1000e/e1000.h  |  4 ----
 drivers/net/ethernet/intel/e1000e/netdev.c |  8 --------
 drivers/net/ethernet/intel/e1000e/param.c  | 16 +++++++++++++++-
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/e1000.h b/drivers/net/ethernet/intel/e1000e/e1000.h
index 98e68888abb1..2311b31bdcac 100644
--- a/drivers/net/ethernet/intel/e1000e/e1000.h
+++ b/drivers/net/ethernet/intel/e1000e/e1000.h
@@ -94,10 +94,6 @@ struct e1000_info;
  */
 #define E1000_CHECK_RESET_COUNT		25
 
-#define DEFAULT_RDTR			0
-#define DEFAULT_RADV			8
-#define BURST_RDTR			0x20
-#define BURST_RADV			0x20
 #define PCICFG_DESC_RING_STATUS		0xe4
 #define FLUSH_DESC_REQUIRED		0x100
 
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 327dfe5bedc0..47b89aac7969 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -3223,14 +3223,6 @@ static void e1000_configure_rx(struct e1000_adapter *adapter)
 		 */
 		ew32(RXDCTL(0), E1000_RXDCTL_DMA_BURST_ENABLE);
 		ew32(RXDCTL(1), E1000_RXDCTL_DMA_BURST_ENABLE);
-
-		/* override the delay timers for enabling bursting, only if
-		 * the value was not set by the user via module options
-		 */
-		if (adapter->rx_int_delay == DEFAULT_RDTR)
-			adapter->rx_int_delay = BURST_RDTR;
-		if (adapter->rx_abs_int_delay == DEFAULT_RADV)
-			adapter->rx_abs_int_delay = BURST_RADV;
 	}
 
 	/* set the Receive Delay Timer Register */
diff --git a/drivers/net/ethernet/intel/e1000e/param.c b/drivers/net/ethernet/intel/e1000e/param.c
index 6d8c39abee16..bb696c98f9b0 100644
--- a/drivers/net/ethernet/intel/e1000e/param.c
+++ b/drivers/net/ethernet/intel/e1000e/param.c
@@ -73,17 +73,25 @@ E1000_PARAM(TxAbsIntDelay, "Transmit Absolute Interrupt Delay");
 /* Receive Interrupt Delay in units of 1.024 microseconds
  * hardware will likely hang if you set this to anything but zero.
  *
+ * Burst variant is used as default if device has FLAG2_DMA_BURST.
+ *
  * Valid Range: 0-65535
  */
 E1000_PARAM(RxIntDelay, "Receive Interrupt Delay");
+#define DEFAULT_RDTR			0
+#define BURST_RDTR			0x20
 #define MAX_RXDELAY 0xFFFF
 #define MIN_RXDELAY 0
 
 /* Receive Absolute Interrupt Delay in units of 1.024 microseconds
+ *
+ * Burst variant is used as default if device has FLAG2_DMA_BURST.
  *
  * Valid Range: 0-65535
  */
 E1000_PARAM(RxAbsIntDelay, "Receive Absolute Interrupt Delay");
+#define DEFAULT_RADV			8
+#define BURST_RADV			0x20
 #define MAX_RXABSDELAY 0xFFFF
 #define MIN_RXABSDELAY 0
 
@@ -297,6 +305,9 @@ void e1000e_check_options(struct e1000_adapter *adapter)
 					 .max = MAX_RXDELAY } }
 		};
 
+		if (adapter->flags2 & FLAG2_DMA_BURST)
+			opt.def = BURST_RDTR;
+
 		if (num_RxIntDelay > bd) {
 			adapter->rx_int_delay = RxIntDelay[bd];
 			e1000_validate_option(&adapter->rx_int_delay, &opt,
@@ -307,7 +318,7 @@ void e1000e_check_options(struct e1000_adapter *adapter)
 	}
 	/* Receive Absolute Interrupt Delay */
 	{
-		static const struct e1000_option opt = {
+		static struct e1000_option opt = {
 			.type = range_option,
 			.name = "Receive Absolute Interrupt Delay",
 			.err  = "using default of "
@@ -317,6 +328,9 @@ void e1000e_check_options(struct e1000_adapter *adapter)
 					 .max = MAX_RXABSDELAY } }
 		};
 
+		if (adapter->flags2 & FLAG2_DMA_BURST)
+			opt.def = BURST_RADV;
+
 		if (num_RxAbsIntDelay > bd) {
 			adapter->rx_abs_int_delay = RxAbsIntDelay[bd];
 			e1000_validate_option(&adapter->rx_abs_int_delay, &opt,
-- 
2.14.1.342.g6490525c54-goog